The principal application area for computer image generation has been that of visual training and/or entertainment simulators which present scenes to a trainee or game player (the operator) that allow him to practice some task such as flying an airplane. In a flight simulator, a three-dimensional model of the desired "gaming area" is prepared and stored in the computer. This model is called the visual data base. The visual simulator combines an image generator with a display device such as a cathode ray tube (CRT) or liquid crystal display (LCD). The image generator converts the three-dimensional visual data base into a two-dimensional scene for display on the display device. The generated imagery is meant to be representative of the true scenes that the operator would see if the operator were actually performing the task being simulated. The generation of display images is said to be in "real time" if the images are updated fast enough to give a sense of motion.
Real-time generation of visual scenes is usually a compromise between realism and the cost of the hardware. What has been needed is a technique for real-time generation of visual displays without sacrificing realism or requiring expensive hardware.